ABSTRACT
This chapter considers substitutability, defines how in the psyche it serves to relate courses of action to each other, and elaborates how this impacts behaviour. It describes how few bits of informs to psychologists about "basic" non-substitutability, about which heuristic theory in cognitive psychology may inform them. The chapter also considers pertains to the polar contrary of substitutability – complementarity. Non-substitutability on the other hand allows psychologists to make sense of the constraints in the psyche on the ability to induce behavioural change in quasi-fixed environments. Considering the dynamics of behaviour, it will be interesting to consider a factor in the psyche which is of some significance in quasi-fixed environments, where but a few bits of information is subject to variation. A further, "deeper", more "fundamental" non-substitutability exists because of the distinction of need from want as behavioural drives. While it is strictly speaking not of the spectrum of substitutability, complementarity is still a form of non-substitutability.
